In general, the term ‘ice cream’ means a frozen dessert obtained after mixing and homogenizing dairy products, such as milk, with flavoring ingredients. Although ice cream was served classically as a dessert in the West, it is regarded as an item of personal today. Some ice cream having a high nutritional value, particularly ice cream with a high fat content, has a calorie of 200 kcal per 100 g. Ice cream is used not only as a snack or dessert but also as a diet for patients or babies.
It is known that ice cream was designed first in around 1550 in Italy and distributed to many European countries. At that time, ice cream had a large ice crystal size like a today's sherbet. Since the 18th century, ice cream has been made by mixing cream with egg yellow and sweeteners under stirring, followed by freezing, so that it has been allowed to have a fine ice crystal size and a soft taste like a today's ice cream. After that time, concentrated milk, condensed milk or powdered milk has been used in addition to cream, while freezing machines have been developed. Under these circumstances, ice cream has been produced in an industrial scale. A method for preparing such ice cream basically includes mixing milk or other dairy products with saccharides, flavoring agents and other side ingredients; homogenizing, sterilizing, cooling and aging the resultant mixture; and stirring the resultant product to incorporate air thereto, followed by freezing. Broadly, such basic methods are classified into European self-made type methods and American industrial methods. The former includes mangling egg yellow, fresh cream, or the like, sufficiently before freezing and provides a deluxe taste, while the latter is focused on nutritional effects and ice cream as a dairy product and provides ice cream products accessible easily in quantity.
As ice cream has broadened applications in various fields beyond its use as a dessert or snack, many attempts have been made to develop novel ice cream ingredients, processing technologies and mixing technologies. Particularly, since ice cream contains a significant amount of sweeteners and fats to satisfy personal preference, it has high-calorie characteristics due to such an ingredient composition. Thus, such ice cream does not meet modern sense about food intake closely related to health, because it is particularly known that excessive calorie intake results in side effects, including obesity and hyperlipidemia.
To overcome this, many attempts have been made to introduce various, functional materials into ice cream. However, most of such functional materials are not suitable in terms of ice cream properties with which a high personal preference is accomplished, since they are not amenable to micronization of ice cream ingredients, homogeneous and stable mixing and sufficient foaming. Although liquid functional extract has been used to accomplish homogeneous and stable mixing, such extracts frequently affect a flavor of ice cream, thereby causing ice cream to lose its value as a personal item. Under these circumstances, many attempts have been made to develop ingredients and processes capable of solving the problems of high calorie of milk fats and a greasy taste thereof while not adversely affecting the preference to ice cream itself. As a part of such attempts, some processes of substituting milk fats used in ice cream with cereal starch, particularly with rice or unpolished rice have been provided.
In terms of nutrition, rice contains various nutrients, including carbohydrates, proteins, lipids, minerals and vitamins. Although rice has a protein content of 6% to 7%, which is lower than that of wheat, it is regarded as a high-quality protein source like soybeans. In addition, rice contains Vitamin B, Vitamin E, dietary fibers, phosphorous, magnesium, etc. Carbohydrates in rice occupy the highest proportion and are substantially composed of starch. As minerals, rice contains a relatively large amount of phosphorus and a relatively small amount of calcium. Therefore, it can be seen that rice is sufficient to substitute for fat ingredients, and is a high-quality food having a good balance of nutrients.
Further, rice starch is suitable for preparation of ice cream, as compared to other ingredients. Particularly, rice starch is advantageous in that it does not affect main characteristics of ice cream, such as a chewing taste or soft texture of ice cream. Rice flour, particularly starch as a main ingredient of rice flour, having such properties has been used to prepare ice cream according to the related art. For example, Korean Unexamined Patent Publication No. 1993-0022962 discloses a method for preparing a rice ice cream. The method includes: pulverizing rice to rice flour having an average particle diameter of 50 μm to 300 μm; dipping the rice flour into water and/or milk at room temperature to allow swelling of rice flour; heating and boiling the resultant solution in which the rice flour is swelled and dipped to obtain a homogeneous rice paste; and mixing the rice paste obtained right after the preceding operation with a homogeneous powdery mixture containing a sweetening agent and milk to provide a homogeneous ice cream mix.
The above-mentioned method has some advantages in that it dose not require the use of a stabilizer, sterilization operation and homogenization operation. However, the method is problematic in that the ice cream mix has an increased viscosity as the starch ingredient (i.e., rice) undergoes gelatinization, resulting in degradation of homogeneity during the preparation of mix, thereby adversely affecting the texture of a frozen ice cream.
In addition, Korean Patent Publication Nos. 0489927, 0489928 and 0489929 disclose a method for forming an ice cream from an ice cream mix obtained by mixing and homogenizing rice slurry formed by adding alpha-amylase to rice flour, sugar, starch syrup, milk cream, powdered skim milk, a stabilizer, fruit concentrate and water. It is stated that the method provides an improved texture of ice cream upon eating by decreasing the viscosity of gelatinized starch particles through the addition of alpha-amylase to rice.
Meanwhile, Korean Unexamined Patent Publication No. 2004-0081728 discloses a method for preparing an ice cream containing polished rice or black rice. The method includes pulverizing polished rice or black rice by a pulverizer, boiling the pulverized rice after mixing it with milk in a cooking pot; and mixing the cooked rice with a mixed base to provide ice cream.
All of the above-mentioned methods according to the related art are based on a decrease in viscosity of starch particles through the use of amylase, and on improvement of texture of ice cream upon eating. However, they are problematic in terms of a harmony between rice and milk fats and ice cream hardness.
In conclusion, although ice cream containing rice substituting for milk fat is slightly advantageous in terms of nutritional effects, as compared to ice cream essentially containing milk fats, it still uses powdered skim milk, dried whole milk, emulsifiers, etc. Therefore, such ice cream still has a high crude fat content, thereby adversely affecting an ice cream taste. Furthermore, repeated intake of such ice cream causes an increase in fat intake in vivo.